The invention relates to a parenterally administrable drug having thrombolytic activity and containing activated protein C free of thrombin activity and of antibodies directed against protein C or activated protein C.
These drugs may be applied as thrombolytic agents, as fibrinolytic agents and as anticoagulants as well as in the treatment of protein C-deficiencies.
Protein C is a vitamin K-dependent glycoprotein that is synthesized in the liver and circulates in plasma as an inactive zymogen at a concentration of 4 .mu.g/ml. It is converted into the active serine protease (activated protein C) by the thrombin-thrombomodulin complex on the surface of the vessel wall (endothelium). It is known that activated protein C has profibrinolytic properties. It also has an anticoagulant effect, because it proteolytically degrades both factor Va, the cofactor for the factor Xa-induced prothrombin activation (thrombin formation), and factor VIIIa, the cofactor for the factor IXa-induced factor X activation.
The activation of protein C in vivo constitutes a negative feedback reaction in the generation of thrombin. In order to develop the optimum biologic activity, a co-factor (protein S) is necessary.
In the PCT Publication WO 90/12028 as well as in EP-A - 0 287 028, methods of activating protein C and affinity chromatographic purification are described. According to EP-A - 0 287 028, the reaction of protein C with thrombin/thrombomodulin is stopped by the addition of antithrombin III.
When administering protein C preparations purified on non-sterile monoclonal antibodies by way of affinity chromatography, there is the danger of transmitting pathogens. In addition, impurities, such as traces of thrombin, traces of murine proteins or serum amyloid P may have adverse effects in the administration of preparations that contain activated protein C.
To increase the virus safety of protein C preparations it is suggested in "Advances in Applied Biotechnology Series", Vol. 11, "Protein C and Related Anticoagulants" (Bruley D. F. and Drohan W. N. eds), Gulf Publishing Company, Houston, London, Paris, Zurich, Tokyo, pp. 83-89 (1990), to isolate protein C from a previously virus inactivated starting material by affinity chromatographic purification on virus inactivated monoclonal antibodies. Subsequently, the preparation may be subjected to a further treatment for virus inactivation.
From PCT Publication WO 90/07524 it is known that serum amyloid P can be eliminated by adsorption of protein C on an ion exchanger (SEPHADEX Q50).
Furthermore, activated protein C can be freed from traces of thrombin by the selective adsorption of the thrombin on heparin-SEPHAROSE (Thromb. Res. 59, 27-35 (1990)). However, that method does not comprise any step for virus inactivation or for the removal of serum amyloid P.
In EP-A - 0 318 201 it is stated that activated protein C alone or in combination with a thrombolytically active substance may be used to prevent arterial thromboses or thromboembolic conditions. The antithrombotic activity of activated protein C is demonstrated by examples.